/*
 * Javassist, a Java-bytecode translator toolkit.
 * Copyright (C) 1999- Shigeru Chiba. All Rights Reserved.
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License.  Alternatively, the contents of this file may be used under
 * the terms of the GNU Lesser General Public License Version 2.1 or later,
 * or the Apache License Version 2.0.
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 */

package com.feilong.lib.javassist.expr;

import com.feilong.lib.javassist.CannotCompileException;
import com.feilong.lib.javassist.ClassPool;
import com.feilong.lib.javassist.CtBehavior;
import com.feilong.lib.javassist.CtClass;
import com.feilong.lib.javassist.NotFoundException;
import com.feilong.lib.javassist.bytecode.BadBytecode;
import com.feilong.lib.javassist.bytecode.Bytecode;
import com.feilong.lib.javassist.bytecode.CodeAttribute;
import com.feilong.lib.javassist.bytecode.CodeIterator;
import com.feilong.lib.javassist.bytecode.ConstPool;
import com.feilong.lib.javassist.bytecode.MethodInfo;
import com.feilong.lib.javassist.bytecode.Opcode;
import com.feilong.lib.javassist.compiler.CompileError;
import com.feilong.lib.javassist.compiler.Javac;
import com.feilong.lib.javassist.compiler.JvstCodeGen;
import com.feilong.lib.javassist.compiler.JvstTypeChecker;
import com.feilong.lib.javassist.compiler.ProceedHandler;
import com.feilong.lib.javassist.compiler.ast.ASTList;

/**
 * Explicit type cast.
 */
public class Cast extends Expr{

    /**
     * Undocumented constructor. Do not use; internal-use only.
     */
    protected Cast(int pos, CodeIterator i, CtClass declaring, MethodInfo m){
        super(pos, i, declaring, m);
    }

    /**
     * Returns the method or constructor containing the type cast
     * expression represented by this object.
     */
    @Override
    public CtBehavior where(){
        return super.where();
    }

    /**
     * Returns the line number of the source line containing the
     * type-cast expression.
     *
     * @return -1 if this information is not available.
     */
    @Override
    public int getLineNumber(){
        return super.getLineNumber();
    }

    /**
     * Returns the source file containing the type-cast expression.
     *
     * @return null if this information is not available.
     */
    @Override
    public String getFileName(){
        return super.getFileName();
    }

    /**
     * Returns the <code>CtClass</code> object representing
     * the type specified by the cast.
     */
    public CtClass getType() throws NotFoundException{
        ConstPool cp = getConstPool();
        int pos = currentPos;
        int index = iterator.u16bitAt(pos + 1);
        String name = cp.getClassInfo(index);
        return thisClass.getClassPool().getCtClass(name);
    }

    /**
     * Returns the list of exceptions that the expression may throw.
     * This list includes both the exceptions that the try-catch statements
     * including the expression can catch and the exceptions that
     * the throws declaration allows the method to throw.
     */
    @Override
    public CtClass[] mayThrow(){
        return super.mayThrow();
    }

    /**
     * Replaces the explicit cast operator with the bytecode derived from
     * the given source text.
     *
     * <p>
     * $0 is available but the value is <code>null</code>.
     *
     * @param statement
     *            a Java statement except try-catch.
     */
    @Override
    public void replace(String statement) throws CannotCompileException{
        thisClass.getClassFile(); // to call checkModify().
        @SuppressWarnings("unused")
        ConstPool constPool = getConstPool();
        int pos = currentPos;
        int index = iterator.u16bitAt(pos + 1);

        Javac jc = new Javac(thisClass);
        ClassPool cp = thisClass.getClassPool();
        CodeAttribute ca = iterator.get();

        try{
            CtClass[] params = new CtClass[] { cp.get(javaLangObject) };
            CtClass retType = getType();

            int paramVar = ca.getMaxLocals();
            jc.recordParams(javaLangObject, params, true, paramVar, withinStatic());
            int retVar = jc.recordReturnType(retType, true);
            jc.recordProceed(new ProceedForCast(index, retType));

            /*
             * Is $_ included in the source code?
             */
            checkResultValue(retType, statement);

            Bytecode bytecode = jc.getBytecode();
            storeStack(params, true, paramVar, bytecode);
            jc.recordLocalVariables(ca, pos);

            bytecode.addConstZero(retType);
            bytecode.addStore(retVar, retType); // initialize $_

            jc.compileStmnt(statement);
            bytecode.addLoad(retVar, retType);

            replace0(pos, bytecode, 3);
        }catch (CompileError e){
            throw new CannotCompileException(e);
        }catch (NotFoundException e){
            throw new CannotCompileException(e);
        }catch (BadBytecode e){
            throw new CannotCompileException("broken method");
        }
    }

    /*
     * <type> $proceed(Object obj)
     */
    static class ProceedForCast implements ProceedHandler{

        int     index;

        CtClass retType;

        ProceedForCast(int i, CtClass t){
            index = i;
            retType = t;
        }

        @Override
        public void doit(JvstCodeGen gen,Bytecode bytecode,ASTList args) throws CompileError{
            if (gen.getMethodArgsLength(args) != 1){
                throw new CompileError(Javac.proceedName + "() cannot take more than one parameter " + "for cast");
            }

            gen.atMethodArgs(args, new int[1], new int[1], new String[1]);
            bytecode.addOpcode(Opcode.CHECKCAST);
            bytecode.addIndex(index);
            gen.setType(retType);
        }

        @Override
        public void setReturnType(JvstTypeChecker c,ASTList args) throws CompileError{
            c.atMethodArgs(args, new int[1], new int[1], new String[1]);
            c.setType(retType);
        }
    }
}
